My experience is just about anything can kill an m8. I've killed them with cannon, 50 cal. One time, in Allies vs. Axis, I even killed one with 30 cal from a Mark 1 Spit or Hurri. That was a surprise.
Most gvs like jeeps and m16s are fairly easy kills, as we all know. I do have problems, though, actually killing any armored vehicles with 50 cal or cannons. I can usually get them smoking and get the kill when they ditch but, even with an IL2, I seem to have a tough time actually blowing up a tank or flak.
That's one reason I started experimenting in earnest with the b25 and have gotten pretty decent with it. You're right, though, they're so sluggish they fall easy prey to flak. By the time you're close enough to identify the target, you're in their kill range and it's all you can do to get out of range before they hit you. As a result, I've been trying to hit them from far enough out they can't hit me.
The cannon on the B25H is supposed to have a range of 5000 yards. Problem is, you have to have the target well identified early so you can tell which dot in the landscape to aim at. I've hit a few gvs from far out and was pretty proud of myself when I took out a wirblewind turret from around 2000 yards the other day. I just wish I could do it more than once out of 100 shots.
